1. Field of the Invention
The present invention relates to a backlight module and a display device with a two-sided light emitting structure, and more specifically, to a backlight module and a display device with a plurality of light emitting diodes disposed on two sides of a flexible circuit board respectively to achieve two-sided lighting effect.
2. Description of the Prior Art
Since liquid crystal is incapable of emitting light, so a backlight module can be regarded as a key component of a liquid crystal display (LCD) panel. The major function of the backlight module is to provide a light source with sufficient brightness and uniform distribution, so as to make the LCD panel display images normally. As the LCD panels are applied to many progressing electronics, such as monitors, notebook computers, digital cameras, projectors and so on, demands of the backlight modules and related components thereof are increasing continuously. The application of light emitting diodes (LEDs) has been developed continuously in past few years. The LEDs belong to cold light, so the LEDs have the advantages of low power consumption, long term service life, without warming up time, rapid reaction speed, small size, durable for vibration, suitable for mass production, being minimized or array-arranged to conform with the demands easily, such that the LEDs have been applied as the light sources of the backlight modules widely.
Generally speaking, the backlight modules with a two-sided light emitting structure can be applied to compact products, such as LCD TV, notebook computers and so on, or to outdoor display devices, such as a large billboard. The backlight module with the two-sided light emitting structure can provide two-sided displaying effect with one set of light sources. The conventional two-sided backlight module mostly utilizes the cold cathode fluorescent lamp (CCFL) as the light source. However, the CCFL has the drawbacks of bad color rendering, high driven voltage, environmental pollution with mercury, emitting ultraviolet light, slow starting speed, light tubes broken easily, difficulty in controlling chroma, and so on. Therefore, the LEDs are taken as the light resource of the two-sided backlight module to solve the drawbacks mentioned above. Please refer to FIG. 1. FIG. 1 is a schematic diagram of a conventional two-sided backlight module 10. The two-sided backlight module 10 includes two LED light bars 12. Each LED light bar 12 includes a base 14 and a plurality of light emitting diodes 16 disposed on the base 14. The base 14 is usually made of aluminum material or fiber glass material for supporting the plurality of light emitting diodes 16. In order to get the effect of the two-sided backlight, the two-sided backlight module 10 requires the double LED light bars 12, so as to increase manufacture cost and assembly thickness. Besides, the aluminum base or fiber glass base requires extra wires to electrically connect to a DC power supply, so as to provide electric power for the LED light bars 12, and it increases cost as well. Furthermore, in order to enhance the dissipating efficiency of the two-sided backlight module 10, a metal plate 18 is usually disposed between the two LED light bars 12. The two LED light bars 12 can be attached on two sides of the metal plate 18. Accordingly, the metal plate 18 can dissipate heat generated by the plurality of light emitting diodes 16 of the two LED light bars 12, but the metal plate 18 also increases the total assembly thickness. Thus, design of a two-sided light emitting backlight module with low cost and small size is an important issue nowadays.